Blasting apparatus



Aug. 17,1937. R. PRICE BLASTING APPARATUS Filed Jan. 17, 1936 2Sheets-Sheet 1 Aug. 17, 1937. R p E 2,089,981

BLASTING APPARATUS Filed Jan. 17, 1936 2 Sheets-Sheet 2 2665 F311].floss/qr PRICE Patented Aug. 17, 1937 UNI-TED STATES PATENT OFFICE 6Claims.

The invention relates to blasting apparatus designed primarily for usein firing blasting charges within mines, although the invention is notrestricted to this particular field of use.

A twin-wire charge-firing cable is wound on a reel within asuitablehand-carried casing, and a charge-firing switch is provided forconnecting said cable with a source of current (battery or magneto) tocomplete the firing circuit, and the principal object of the inventionis to prevent closing of said charge-firing switch until such a lengthof the cable has been unwound from the reel (by carrying the casing awayfrom the charge) as to insure the safety of the person carrying saidcasing, against injury from the blast.

For safety, it has long been required that the ends of the two wires ofthe blasting cable remote from the cap-engaging end of said cable,

0 be conductively connected with each other before connecting said wireswith the cap, and a further object of the invention is to prdvide anormally closed safety switch for this purpose, which cannot be openeduntil the aforesaid length of cable has been unwound from the reel.

Yet another object is toprovide an apparatus in which closing of thefiring switch effects opening of the aforesaid safety switch.

A still further object is to provide an arrangement of indicatingnumbers which will show to mine inspectors the exact number of feet ofcable connected with the reel. Thus, without measuring, an inspector maydetermine whether the cable is as long as required or whether it hasbeen shortened, due for instance, to injury, splicing,

etc.

With the foregoing and minor objects in view, the invention resides inthe novel subject matter hereinafter described and claimed, descriptionbeing accomplished by reference to the accompanying drawings.

Fig. 1 is a side elevation.

Fig. 2 is an edge view with the blasting cable partially unwound fromthe reel.

Fig. 3 is arr enlarged vertical sectional view on line 3--3 of Fig. 1.

Fig. 4 is an enlarged elevation showing the switch and its locking meansin the positions which they occupy while the firing cable is wound 'uponthe reel.

Fig. 5 is a view similar to Fig. 4 but illustrating the switch-lockingmeans in released position.

Fig. 6 is an elevation of the switch base and its load terminals orcontacts, the rotatable switch member and the switch cap being removed.

Fig. 7 is an inner side elevation of the cap and switch member.

Fig. 8 is an inner side elevation of the switch cap.

Fig. 9 is an elevation of the rotatable switch member.

Fig. 10 is a sectional view through the assembled switch substantiallyon line l0l0 of Fig. 6.

Fig. 11 is a detail sectional view on line n of Fig. 6. I

The form of construction selected for illustration in the presentapplication will be rather specifically described, with theunderstanding however, that within the scope of the invention asclaimed, numerous variations may be made.

A casing I2 is provided containing a reel I3 for a twin-wirecharge-firing cable I4, the end of this cable which is adapted forconnection with the cap, being preferably provided with a flexiblemetallic armor l5 to prevent injury thereto when a blast is fired.

One side of the reel I3 is provided with two contact rings l6 and I!which are insulated therefrom, and one side of the casing l2 carries twocontact rings l8 and i9, these rings being insulated from the casing andbeing disposed in contact with said rings it and i1 respectively. One ofthe wires 20 of the cable i4 is connected with the ring I6 and the otherwire 2| of said cable is connected with the ring ii. A wire 22 isconnected with the ring i8 and a wire 23 is connected with the ring i9,said wires 22 and 23 leading to the exterior of the casing l2 and to aswitch 24. Two leads 25 and 26 extend to this switch from a battery 21or some other desired source of current. connects the leads 25 and 28from the wires 22 and 23 and conductively connects these two wires 22and 23 with each other. Since these wires 22 and 23 are connectedconductively with the two wires 20 and 21 of the cable l4, these wires2!! and 2i are thus conductively connected with each other in accordancewith safety requirements. When the switch 24 is actuated to conductivelyconnect the lead 25 with the wire 22 and the lead 26 with the wire 23,said switch disconnects the Wires 22 and 23 from each other so that theblasting circuit is completed. Features of switch constructionpreferably used in producing the desired operation, will be hereinafterexplained, but it may here be stated that the switch dis- Normally,,theswitch 24 disclosed is of a rotatable type and includes an actuatingshaft 28. Novel provision is made for so holding this shaft as toprevent operation of the switch 24 to fire a charge, until-a predetergmined length of the cable M has been unwound a head 29 having a socket30 into which a key K may be inserted to turn the head and shaft whenrotation of said shaft is permitted by predetermined rotation of thereel I3, .as hereinafter explained. A spring-pressed plunger 3! (Fig.mounted in a suitable fixed plate or the like 32, is preferably receivedin a portion of the key socket 30 to prevent any possible accidentalmovement of the switch, said plunger 31 however, being releasable byinsertion of the key. A spring 33 is preferably provided to eject thekey from the socket 30 when the switch has been restored to its normalposition, and in order that said switch cannot remain in firingposition, a spring 34 is connected with the head 29, it being necessaryto hold the switch in firing pos'ition against-the tension of thisspring, with the result that the spring will again open the switch, andas soon as the switch reaches this normal open position, the plunger 3|locks it and the spring 33 ejects the key.

Operation of the switch bygmeans of the key is normally prevented bynovel mechanism releasable only by predetermined rotation of the reell3. A locking disk 35 is mounted on a shaft 36 parallel with the switchshaft 28 and the reel shaft 31, the head 29'on said switch shaft bee ingprovided with a curved edge '38 which en- 9 gages the edge of saidlocking disk 35 (Fig. 4)

until said disk as has rotated sufficiently to bring a notch 39 withwhich its edge is provided, opposite said head 29 (Fig. 5). The head 29may (Fig. 3) and by having said nuts positioned within the cover 23. k

Normally, the switch stands in the position at which it disconnects thecable M from the source of current 21 an connects the two wires 20 and2! of said cable onductively with each other. said switch being held inthis position by contact of the edge 38 of the head 29 with the lockthenbe turned by insertion of the key to actuate the switch. The disk 35 isdriven by a train of speed reduction gearing from the reel shaft 31 andit, will thus be seen that said disk will allow operation of the switchto effect charge firing, only when the reel has been rotated to a pre-50 determined extent by unwinding of the chargefiring cable l4therefrom.

In the present showing, the reel shaft 31 is provided with a worm d0meshing with a worm 5 gear 4| on a transverse shaft 42, this-shaft beingprovided with a worm 43 meshing with a worm gear I on the shaft 36 ofthe disk 35. Other gearing however, could of course be employed to causethe reel l3 to drive the switch-locking disk 35. Asuitable yoke 45 hasbeen shown to assist in properly mounting the shaft 36 and possiblyother parts upon the exterior of the casing l2, and the plate or thelike 32 above described, may well be; secured to this yoke.

A hinged cover 46 is preferably provided to contain the switch 24, thedriving gearing for the locking member 35, the locking member itself,

the battery 21 and a number of the wires, said cover being held inclosed position by suitable locking or sealing means 41 to preventtamper- 7 ing with any parts confined within said cover,

Tampering with the reel or other parts withinl the casing l2, may beprevented by so constructing the casing that access to its interiorcannot be had without removing nuts 43 from bolts 9 ing disk 35 as seenin Fig. 4. With the switch thus held, the cable I4 is connected with'the charge to be fired. The casing I2 is then carried, by means of asuitable handle 50', away from the charge, causingunwinding of the cableII from the reel l3. By the time 'a predetermined amount of this cablehas been unwound from the reel, this reel has caused the gearing 40, ll,43 and M to drive the disk 35 to the position shown in Fig. 5. Theswitch may then be operated by means of thekey, which;v key is passedthrough a suitable key-hole 5| in the cover 46. When the key isinserted, it releases the tumbler or plunger 3| and by means of the key,the switch may then .be operated to cause disconnection of the wires 20and 2| from each other and to conductively connect these wires with thecurrent source 21, causing firing of the charge. When pressure on thekey is released, the spring 34 restores the switch to its normalposition and the spring 33 ejects-the key. The cable I! is then rewoundupon the reel l3 by turning the hand crank 52, the charge having beenfired. During this rewinding, the locking disk 35 returns to itsoriginal position? Rewinding of the cable by rotating thereel l3 in theimproper direction, may be prevented by providing this locking disk witha stop 53 which will strike the knob 29 as seen in Fig. 5.

I preferably provide an arcuate series of numbers on the locking disk 35as denoted at 5| in Figs. 4 and-5, said numbers being successivelyvisible through a view opening 55 in the cover- 48 as said locking diskrotates. The numbers represent units of measurement, preferably feetandthey range, from zero to the maximum number of feet of cable ll whichthe device is to carry. When the cable is entirely unwound from the reelor unwound as far as possible, zero appears in the opening 55 indicatingthat there is then practically. no cable upon the reel. If

twenty feet of cable be returned into the casingi2, 20 will appearin theopening 55, etc. Thus, if the cable should be say-one hundred and tenfeet long, "110 will appearin the opening 55 when the cableis fullywound on the reel and a mine inspector seeing this, would know that thecable was of the required length. If he inspected the device with thecable fully wound and found that-'l00" instead of 110" appeared in theopening 55, he would know that the cable had been shortened ten feet andthe device would therefore be rejected instead of passed,

until the deficiency had been corrected. 2

The switch 24 in the present disclosure, in-

cludes a'base 51, a cap '53 and a rotatable switch member 59 betweensaid cap and base. The cap and base are secured together by any suitablemeans and the entire switch is mounted in any preferred manner, and theswitch member 59 is keyed to or otherwise connected with the shaft.

23 to be rotated by the latter. The base 51 carries two load terminalsor contacts BI and 32 which are connected with the wires 22 and 23respectively. The cap' 58 carries two lead terminals or contacts and.which are connected with the wires 25 and 26 respectively. The switchmember 59 carries two contacts'65 and 66 located at one side onlythereof, said contacts being connected by a conductor 61. When theswitch is in its normal position, contact 65 lies against the terminalor contact 6 and contact '66 similarly engages the terminal or contact62. Thus,

by means of 6|, 65, 61, 66 and 62, the wire 22 is conductively connectedwith the wire 23, for 10 safety.

The switch member 59 carries two other contacts 68 and 68 which extendentirely therethrough. when this switch member is rotated by the key,contact 68 engages the contact 6| and the contact 63, and contact 69engages the contact 62 and the contact 64. Thus current may fiow fromwire 25 through 63, 68 and 6| to wire 22 and current can fiow from wire26 through 64, 69 and 62 to wire 23, completing the firing circuit.

I prefer to mount spring-pressed insulating buttons 10 in the terminalsor contacts 6|, 62, 63 and 64 preventing the contacts 68 and 69 fromengaging said terminals or contacts unless the switch member 59 isforcibly turned. Thus, should any unusual occurrence free the switchmember 59 from the locking means, the firing circuit could not becompleted by accidental rotation of said switch member.

From the foregoing, it will be seen that novel provision has been madefor carrying out the objects of the invention but attention is again invited to the possibility of making numerous variations over theconstruction herein disclosed.

I claim:

1. A blasting apparatus comprising a reel, a current-conductingcharge-firing cable securedto and wound on said reel, normally openchargefiring contact means for connecting said cable with a source ofcurrent when closed, additional normally closed contact means forconductively connecting the two conductors of said firing cable witheach other until the charge is to be fired, and reel-driven controlmeans for both of said contact means constraining them to remain intheir normal positions until said reel has rotated sufiiciently to payout a predetermined length of said cable and for then freeing saidcontact means to permit actuation thereof.

2. A blasting apparatus comprising a reel, a current-conductingcharge-firing cable secured to and wound on said reel, normally openchargefiring contact means for connecting said cable with a source ofcurrent when closed, and addi- 55 tional normally closed contact meansfor conductively connecting the two conductors of said firing cable witheach other until the charge is to be fired, locking means for both ofsaid contact means operatively connected with said reel,

60 and reel-driven means for releasing said locking means only when saidreel has been rotated to a predetermined extent.

3. A blasting apparatus comprising a reel, a current-conductingcharge-firing cable secured to 65 and wound on said reel, normally openchargefiring contact means, controlling means for said charge-firingcontact means active to hold the same open until said reel has beenrotated to a predetermined extent and to then free said 70 charge-firingcontact means for operation, said charge-firing contact means beingconnected with said cable and with a source or current to complete thecharge-firing circuit when closed, and normally closed contact meansoperatively connected with said charge-firing contact means and movableto open position by closing of said charge-firing contact means, saidnormally closed contact means being so connected with the two conductorsof the charge-firing cable as to conductively connect said conductorswith each other prior to opening of said normally closed contact means.

4. A blasting apparatus comprising a currentconducting charge-firingcable for connection with a charge to be fired, a reel upon which saidcable is wound, a carrier for said reel by means of which the blastercarries said reel away from the charge to unwind the cable afterconnecting said cable with said charge, a switch for completing 'thecharge-firing circuit, andmeans actuated by the cable-unwindingoperation for preventing closing of said switch until said reel hasrotated sufiiciently to pay out a length of cable long enough to reach asafe distance from the charge, and for freeing said switch for operationwhen said reel has rotated to said extent, whereby if the blaster hasunwound said length of cable by carrying said carrier away from thecharge, he will be at a safe distance from said charge when said switchmeans is freed for operation.

5. A blasting apparatus comprising a chargefiring current-conductingcable for connection with a charge to be fired, a reel upon which saidcable is wound, a carrier for said reel by means of which the blastercarries said reel away from the charge to unwind the cable afterconnecting said cable with said charge, a switch for completing thecharge-firing circuit, a movably mounted locking member for holding saidswitch open until said locking member has been moved to a predeterminedreleased position, and means driven by said reel for disposing saidlocking member at said released position only when said reel has rotatedsuificiently to pay out a length of cable long enough to reach a safedistance from the charge, whereby if the blaster has unwound said lengthof cable by carrying said carrier away from the charge, he will be at asafe distance from said charge when said locking member reaches saidreleased position.

6. A blasting apparatus comprising a currentconducting charge-firingcable for connection with a charge to be fired, a reel upon which saidcable is wound, a carrier for said reel by means of which the blastercarries said reel away from the charge to unwind the cable afterconnecting said cable with said charge, a switch for completing thecharge-firing circuit, a rotatable looking member mounted on saidcarrier and operatively associated with said switch for holding saidswitch open until said locking member has been rotated to apredetermined released position, and reduction gearing operativelyconnecting said locking member with said reel for slowly rotating saidlocking member toward said released position as the reel is rotatedduring carrying away from the charge, said gearing being such as todispose said locking member at said released position only when saidreel has rotated suificiently to pay out a length of cable long enoughto reach a safe distance from the charge, whereby if the blaster hasunwound said length of cable by carrying said carrier away from thecharge, he will be at a safe distance from said charge when said lockingmember reaches said released position.

ROBERT PRICE.

